Spacecraft Sees Comet, Earth and Mercury Together

A new video from a NASA spacecraft studying the sun has captured an unexpected sight: a wandering comet posing with the planets Earth and Mercury.

The cosmic view comes from one of NASA's twin Stereo spacecraft that constantly watch the sun for signs of solar flares and other space weather events. It shows Mercury and Earth as they appeared with the Comet Pan-STARRS, a comet that is currently visible from the Northern Hemisphere during evening twilight.

According to a NASA description, the video "shows the comet and its fluttering tail as it moves through space." The Earth appears as a bright stationary object on the right side of the video, while Mercury is visible as a moving light on the left side. [How to see Comet Pan-STARRS]

The sun is actually out of the frame in the Stereo-B spacecraft's video, but its solar wind is visible as a stream of material, NASA officials explained. Meanwhile, the view of Comet Pan-STARRS from space is giving scientists a wealth of data to review, they added.

"Comet scientists say the tail looks quite complex and it will take computer models to help understand exactly what’s happening in STEREO’s observations," agency officials said in a video description. "The comet should remain visible to the naked eye through the end of March."

Comet Pan-STARRS is currently visible to stargazers in the Northern Hemisphere just after sunset. To see the comet, look low on the western horizon just after the sun has gone down. Comet Pan-STARRS can appear as a bright head with a wispy trail, weather permitting, though some stargazers have said the bright evening twilight can make spotting it tricky.

The Comet Pan-STARRS was discovered in June 2011 by astronomers using the Panoramic Survey Telescope & Rapid Response System (Pan-STARRS) in Hawaii. The comet's official name is C/2011 L4 (PANSTARRS).

Scientists estimate that Comet Pan-STARRS takes about 110,000 years to orbit the sun after this first swing through the inner solar system. The comet crossed into the Northern Hemisphere evening sky last week after months of being visible to observers in the Southern Hemisphere.

NASA's twin Stereo A and B spacecraft (the name is short for Solar TErrestrial RElations Observatory) observe the sun in tandem to provide unparalleled views of how material from solar eruptions makes its way to Earth. The spacecraft launched in 2006 and are part of a fleet of sun-watching spacecraft that monitor solar storms.

Comet Pan-STARRS is one of several comets gracing the night sky in 2013. Pan-STARRS was joined by the Comet Lemmon earlier this year when both were visible together in the Southern Hemisphere sky. Later this year, the sungrazing Comet ISONcould put on a potentially dazzling display when it makes its closest approach to the sun in late November.

Editor's note: If you snap an amazing photo of Comet Pan-STARRS in the night sky, or any other celestial object, and you'd like to share for a possible story or image gallery, please send images and comments, including location information, to managing editor Tariq Malik at spacephotos@space.com.

This story was updated to correct the orbit of Comet Pan-STARRS, which is thought to be about 110,000 years after this pass around the sun.